Lighting device for a display case

ABSTRACT

A rod-shaped light fitting ( 8 ) for a showcase, whose length corresponds to the distance between two opposite side surfaces ( 4, 6 ) of the showcase which are plane-parallel to one another, comprises a plurality of light-emitting diodes ( 12 ) and can be positioned between the said side surfaces ( 4, 6 ) in such manner that the contacts ( 16 ) fixed in each end ( 9 ) of the rod-shaped light fitting ( 8 ) and electrically connected to the light-emitting diodes ( 12 ) press against the side surfaces ( 4, 6 ) under spring loading and at the same time establish electrical connection with the electrically conductive layer provided on the side of the side surfaces ( 4, 6 ) facing the inside of the showcase, the said layers being connected to a current source. Such a light fitting can be positioned in any desired position in a showcase to illuminate the objects displayed therein.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No.200 08 446.1 filed on May 11, 2000. Applicant also claims priority under35 U.S.C. §365 of PCT/EP01/05177 filed on May 8, 2001. The internationalapplication under PCT article 21(2) was not published in English.

The invention concerns a light fitting for a showcase for the display ofobjects, in which the space accommodating the objects is enclosed byseveral side surfaces at least two of which are opposite andplane-parallel to one another.

Such a light fitting is already known. Thus, in European Patent 0 670129 a showcase with a light fitting is described, in which light fibresfor the illumination of the objects on the tray below end on theunderside of each individual tray, and the said fibres are bundled andpass through a common duct. A drawback with this type of lighting is theneed to have a tray to hold the light fibres. The same applies also inthe case when the light fibres end in the ceiling of the showcase. Inboth cases the type of lighting is determined by the predeterminedarrangement of the outlet openings on the underside of the tray or theceiling, which does not allow any choice of the illumination ofparticular areas or objects in the showcase. However, this can be doneby replacing the tray or the surface forming the ceiling by one in whichthe outlet openings for the light fibres are appropriately arranged.

The purpose of the present invention is to provide a light fitting for ashowcase, which allows flexible illumination of the objects in theshowcase in a simple way.

This objective is achieved in that the light fitting comprises aplurality of light-emitting diodes and is formed as a rod of lengthcorresponding to the distance between two opposite side surfaces whichcan be fixed between these side surfaces by suitable means attached tothe light fitting, the current being supplied to the light fitting viathe side surface(s).

The rod-shaped light fitting can be positioned in any position betweenthe two side faces and can also be removed, so the objects can beilluminated just as desired.

From German utility model G 87 07 283.1 a low-voltage light for shelfpartitions is already known, with vertical supports arranged on eachside of a partition and electrical conductors embedded in the supports,a rod-shaped light carrier track being provided that can be connected ateach end to a conductor to form electrical contact, such that thecurrent lines are connected to at least one bulb on the light carriertrack. In this, the light carrier track can only be attached in the areaof the supports.

A similar lighting arrangement for an item of furniture having verticalwall sections parallel to one another is known from DE 39 18 193 A1. Inthis case current is supplied to a lighting element, which for exampleis incorporated in a cross-member connecting the two wall sections inthe form of an insertion plate, via electrical voltage connectionsdistributed over the height of the wall section which allow connectionto a light element at the respective height chosen. In this lightingarrangement too, attachment is only possible in the area of the voltageconnections.

In addition, in utility model DE 297 17 444 U1 an infra-red-free andultraviolet-free light for goods cooled in a refrigerator is described,in which several rectangular plates having numerous light-emittingdiodes on their underside are attached one after another to railsparallel to the longitudinal dimension of the inside, the said railsbeing mounted on a projection of the refrigerator extending inwards overthe inside space. Nothing further is said about how current is suppliedto the plates carrying the light diodes.

Other advantages emerge from the subordinate claims.

The present innovation is described in more detail below with referenceto an example embodiment illustrated in the drawing, which shows:

FIG. 1: Perspective view of a showcase

FIG. 2: Side view of the light fitting

FIG. 3: Plan view of one end of the light fitting

FIG. 4: Section A—A through the light fitting.

The showcase shown in FIG. 1 consists of a lower portion 2 and an upperportion 3, the said upper portion 3 formed of a left-hand side surface4, a front surface 5, a right-hand side surface 6 and a back surface 7.A surface 17 closing the top, together with the surfaces 4 to 7, formsthe space in which the objects to be displayed are placed, these restingon a bottom surface 18 that closes the said space at the bottom. Atleast the front surface 5 and the closing surface 17 at the top are as arule made of panes of clear glass, and this can also be true of theother side surfaces. The prerequisite for the use of the innovation,however, is that two opposite surfaces, for example the left-hand sidesurface 4 and the right-hand side surface 6, must be plane-parallel toone another. The upper portion 3 can either be large, such that itreaches nearly to the floor, when the lower portion 2 of a free-standingshowcase is made correspondingly low, or it may be at table height whenthe lower portion 2 is made correspondingly high and the upper portionof such a table-top showcase only has a small height. Whereas with atable-top showcase the objects only rest on the bottom surface 18, witha free-standing showcase the objects can also be placed at one or moreintermediate levels positioned one above the other. The use of theinnovation is not restricted to the table-top showcase illustrated inFIG. 1, but can also be used with free-standing showcases. The lightfitting 8 is positioned between two plane-parallel side surfaces (forexample 4 and 6), its length between the two ends 9 corresponding to theinside distance between the two side surfaces.

The light fitting 8 has a plurality of light-emitting diodes 12 (FIGS. 2to 4), preferably ones that emit white light, which are distributedalong the entire length of the light fitting 8. It is also conceivable,however, to arrange the light-emitting diodes 12 in preferred areas or,by incorporating corresponding switching means, to operate them insections that can be switched on or off. The current is supplied to thelight-emitting diodes 12 via the side surfaces between which the lightfitting 8 is positioned. For this purpose the side surfaces (for example4 and 6) which the light fitting 8 touches can either be made completelyof an electrically conducting material, or they can be of an insulatingmaterial coated with an electrically conducting layer on the side facingthe inside space of the showcase. This can even be a pane of glassprovided by vaporisation with a very thin electrically conductive layerwhich is completely or almost completely invisible to the human eye.Electrical connection between the light fitting 8 and the side surfaces(for example 4 and 6) is established by means of one or more ball-typeor spherical contacts 16 mounted under spring loading at one or bothends 9 of the light fitting 8 which, when the light fitting 8 has beenfitted into the inside space of the showcase, press against the insideof the side surface concerned. Current can now be supplied via one orboth ends 9 of the light fitting 8. If the contacts 16 are present atboth ends 9 of the light fitting 8, then one pole of the current source(not shown) is connected to one side surface and the other pole of thecurrent source to the opposite side surface. It is also conceivable,however, to pass the current lead for the light-emitting diodes 12 onlythrough one end 9 of the light fitting, and in this case both poles ofthe current source are correspondingly connected to one side surfaceand, at the side surface in question, the two poles are connected tostrip-shaped surfaces next to or under one another and the contacts 16on the end in question are arranged in a corresponding way. It is alsopossible to provide the side of one or more side surfaces (4 and/or 6)facing the inside space of the showcase with a coating of lacquer and inthis case the contacts 16 are made needle or cone shaped so that theypenetrate through the lacquer layer to make contact.

The light fitting 8 can be held in the desired position between the twoside surfaces (for example 4 and 6) by the contact pressure of thecontacts themselves 16 against the inside of the side surfaces. It isalso conceivable, however, if the two side surfaces are made from amagnetic material such as sheet steel, to provide axially displaceablemagnets 13 at one or both ends 9 of the light fitting 8, each held inits rest position by a spring 14. As soon as the light fitting 8 is inthe desired position between the two side surfaces, it can be fixedthere by the axially displaceable magnets 13. To release the connectionbetween the light fitting and the side surfaces, the respective magnet13 can be detached from the side surface by pulling on the handle 15. Asimilar solution is also possible for the contacts 16, in which casethese too are arranged so that they can move in the axial directionrelative to the light fitting 8 and/or are spring loaded, and when thelight fitting is in its desired position they are brought into contactwith the side surfaces (4, 6) and are released therefrom before thelight fitting is removed. This can also be done by means of a handlesimilar to the handle 15. Depending on the weight of the light fitting8, the spring pressure of the contacts 16 may already be sufficient tohold the light fitting securely between the two side surfaces (forexample 4 and 6).

The rod-shaped housing of the light fitting 8 can for example have acircular, oval or polygonal cross-section (FIGS. 3 and 4) and can eitherbe bent to the corresponding shape from sheet steel or consist of anextrusion. In the area of the light-emitting diodes 12 a mountingsurface 19 is provided close to a through-going opening 11, such that onthe mounting surface 19 a substrate 10 in the form of a printed circuitboard carrying the conducting paths and the light-emitting diodes 12connected thereto is attached. As shown in FIG. 2, the opening 11 canextend almost as far as each end 9, and the housing is then only closedin the area of the springs 14 and magnets 13, while the handle 15 isalready in the opening 11. The opening 11 is provided at the top with ascreen 20 and, when positioned in the showcase, is correspondinglyturned to face the area to be illuminated in the showcase. If needs be,the screen 20 can also be attached to the underside of the opening 11.

1. Light fitting for a showcase for the display of objects, in which thespace containing the objects is enclosed by several side surfaces, atleast two of the said side surfaces being arranged opposite andplane-parallel to one another, wherein the light fitting (8) comprises aplurality of light-emitting diodes (12) and is rod-shaped having twoopposing ends (9) and a length corresponding to the distance betweensaid at lest two opposite and plane-parallel side surfaces (4 and 6) ofsaid showcase, said light fitting (8) including means for removablyfixing said light fitting between said at least two opposite andplane-parallel side surfaces (4 and 6) and further including electricalcontacts (16) arranged on at least one of the opposing ends of saidrod-shaped light fitting (8) in contact with at least one of said atleast two opposite and plane-parallel side surfaces (4 and 6), whereinsaid at least two opposite and plane-parallel side surfaces (4 and 6) ofsaid showcase are electrically conductive so that electric current maybe supplied to said light fitting (8) via said electrical contacts (16)wherever said light fitting (8) is fixed between said at least twoopposite and plane-parallel side surfaces (4 and 6).
 2. Light fittingaccording to claim 1, wherein said at least two opposite andplane-parallel side surfaces (4 and 6) are made of an electricallyconducting material.
 3. Light fitting according to claim 2, wherein saidat least two opposite and plane-parallel side surfaces (4 and 6) consistof sheet steel and at the two ends (9) of the light fitting (8) magnets(13) are attached, which are so formed and mounted that a detachableconnection can be formed between an end (9) of the light fitting (8) andthe corresponding side surface (4, 6).
 4. Light fitting according toclaim 3, wherein the magnet (13) is mounted axially and held in its restposition in each case by a spring (14).
 5. Light fitting according toclaim 4, wherein the magnet (13) can be detached from the side surfaceby means of a handle (15).
 6. Light fitting according to claim 1,wherein one or both of said at least two opposite and plane-parallelside surfaces (4, 6) consists of a glass plate provided with anelectrically conductive layer on the side facing the inside space. 7.Light fitting according to claim 6, wherein the said electricallyconductive layer is transparent.
 8. Light fitting according to claim 1,wherein spring-loaded contacts (16) are mounted at one or both ends (9)of the light fitting (8).
 9. Light fitting according to claim 8, whereinthe contacts (16) are formed in the shape of balls, spheres, needles orcones.
 10. Light fitting according to claim 8, wherein the contacts (16)are mounted axially and are held in the rest position by means of aspring (14), such that they can be detached from said at least twoopposite and plane-parallel side surface (4, 6) by means of a handle.